Which physicists won the 1978 Nobel Prize in Physics for discovering cosmic microwave background radiation?

Arno Penzias and Robert Wilson won the 1978 Nobel Prize in Physics for discovering cosmic microwave background radiation. Their observation provided strong evidence that the universe was once much hotter and denser than it is today.

In 1964, Penzias and Wilson were testing a sensitive microwave antenna at Bell Telephone Laboratories in New Jersey. They detected a persistent background signal arriving from every direction. After eliminating possible sources, including contamination from pigeon nests, they recognized that the signal was cosmic.

The radiation is the cooled remnant of the early universe. As space expanded, the radiation stretched to microwave wavelengths. Its temperature is now about 2.7 kelvin above absolute zero. The discovery supported the hot Big Bang model over competing steady-state ideas.

Penzias and Wilson shared the Nobel Prize with Pyotr Kapitsa, who was honored for low-temperature physics. The later Nobel-winning satellite missions COBE and Planck mapped tiny temperature variations in the background, allowing scientists to study the universe’s early structure in much greater detail.